1. Field of the Invention
The present invention relates to a porous molding containing an odoriferous substance obtained by impregnating a cellulose acetate-based porous molding with at least one odoriferous substance such as an aromatizing agent or a volatile insect repellent by adsorption.
2. Description of the Prior Art
As understood from scent bags, pastilles, etc., means for stably and slowly releasing an odoriferous substance such as a perfume or a volatile insect repellent over a long period of time were devised considerably long time ago.
In recent years, proposals were made of, for example, a process for obtaining a plastic article having an aromaticity by allowing an adsorptive porous powder to adsorb an odoriferous substance, dispersing the powder in a gas-permeable plastic and molding the plastic after pelletization (Japanese Patent Publication No. 6283/1968), and a process comprising incorporating a volatile chemical in a thermoplastic elastomer comprising blocks containing polymer segments having a strong intermolecular bonding force and those having a weak intermolecular bonding force (Japanese Patent Laid-Open No. 115377/1981).
Scent bags, pastilles and the products obtained by the above processes, however, have the drawbacks that their perfume contents are as low as several to about ten %, that the persistence of their fragrance is short and that the fragrance is weak.
When imparting the aromaticity to a plastic article, restrictions are placed on the amount, kind, etc., of the aromatizing agent (perfume) added to the plastic, because it does not usually have sufficient compatibility with plastics, and is easily evaporated during molding after pelletization. In addition, it is difficult to use an easily volatile aromatizing agent.
When the thermoplastic elastomer having blocks comprising polymer segments having a strong intermolecular bonding force and those having a weak intermolecular bonding force is used as a carrier for adsorption and volatilization of a volatile chemical, these is a restriction that a choice must be made of those chemicals and diluents therefor which show an affinity for the polymer segments having a weak intermolecular bonding force but show less affinity for the polymer segments having a strong intermolecular bonding force.
The requirements for a material (carrier) for adsorbing an odoriferous substance and releasing the adsorbed odoriferous substance are as follows. Firstly, the odoriferous substance is chemically inert to the carrier. Secondly, the carrier can fully adsorb the odoriferous substance. Thirdly, the external shape of the carrier does not change substantially after adsorption of the odoriferous substance. Fourthly, the odoriferous substance is released at a moderate rate and the composition of the released component does not change appreciably with the lapse of time. The third requirement that the external shape of a carrier does not change substantially is particularly important for designing commercial products when the carrier comprises a molding.